In a cut-off die set, a shearing blade is used to shear a continuous length of tubing emanating from a tube mill into useful and manageable sections. The shearing apparatus typically comprises a shearing blade fixed or mounted to an upper platen which is mounted on pins for movement relative to a lower platen. As the die set is closed, the shearing blade severs the tubing into predetermined lengths. Both single and double cut die sets are known.
Presently the upper end of the shearing blade is clamped to a blade mounting block fixed to the upper platen of the die set by machine screws. The blade is contained in a recess on the face of the mounting block. Spacers of various thicknesses are disposed between the blade and the mounting block. The spacers are used to align the shearing blade. A clamping plate is used to fasten the shearing blade to the blade mounting block. The clamping plate is fixed to the blade mounting block by threaded fasteners extending through both the clamping plate and shearing blade. The threaded fasteners are received in threaded bores located on the mounting block.
Eventually the cutting surface of the shearing blade becomes dull during the cutting operation. When dull, the shearing blade must be sharpened or replaced in order for the die set to continue operatiing at maximum efficiency. Changing the shearing blade is a time consuming procedure. The operator is required to loosen and remove the clamping plate and screws fastening the blade to the mounting block. When the clamping plate is removed the operator must remove the old blade and insert a new blade in the proper position on the mounting block. Finally the operator must replace the clamping plate and re-tighten the screws thereby fastening the new blade to the mounting block.
The operator must also follow the same time consuming procedure when changing the blade to accommodate different sizes of tubing or when the blade is broken during the cutting operation. Any time savings that can gained while changing the shearing blade results in increased operation time of the mill. As indicated, time is of the essence in the tube cutting industry, tubing continuously emanates from a tube mill at a high rate of speed. Thus, any problems, delays or shutdowns due to repair or replacement of the cutting equipment results in lost production and revenue to the tube maker. Therefore, any time savings that results from ease in maintenance and/or replacement of parts increases the period the mill can be operational, thus increasing production.